Substrate processing apparatus, substrate processing method, fluid supplying method and storage medium

The present disclosure provides a substrate processing apparatus including: a processing chamber configured to process a substrate; a fluid supply source configured to supply a substrate processing fluid used in processing for the substrate in a predetermined pressure; a constant pressure supplying path configured to supply the substrate processing fluid from the fluid supply source to the processing chamber in a predetermined pressure without boosting the pressure of the substrate processing liquid; a boosted pressure supplying path configured to boost the pressure of the substrate processing fluid from the fluid supply source into a predetermined pressure by a booster mechanism and supply the pressure boosted substrate processing fluid to the processing chamber; and a control unit configured to switch over the constant pressure supplying path and the boosted pressure supplying path.